Search for D0 → γγ and improved measurement of the branching fraction for D0 → π0π0 / M. Ablikim, M. N. Achasov, X. C. Ai [et.al.] // Physical Review D. 2015. Vol. 91, № 11. P. 112015-1-112015-10. URL: http://vital.lib.tsu.ru/vital/access/manager/Repository/vtls:000532685